Hi, I am putting my 5.4 back together, I had torn it down to change the crank, rod and main bearings due to a spun rod bearing, anyway, I somehow.....I really dont know how because I know better, mixed up the connecting rod bearing caps when I was putting it back together...I see the white stripe that looks like a marker, but some are worn off the cap so I cant really be sure if I'm matchng the correct cap with the correct rod...so now what do I do? I can see the mating surfaces between the rod and the cap are pretty much invisible and it looks like they match up well...but I dunno if thats a good way to tell if I'm gonna have a problem on my hands or not...any help would be appreciated.---Jack

 

You could have a problem. The caps and rods together fit really tight and if you can push the cap on and have nearly no visible gap on either side you might be alright. Do NOT bolt them together until you know for sure. Rotate the engine to check both sides of the cap. About all you can do is keep trying them until you get a perfect match. They will only get tight if they are the matched pair.
Next time you will remember to mark the rods and caps with a vibrator etcher and not have this problem. RIGHT???

 

Just curious - could you tell why it spun a rod bearing? Lot of miles? Lack of oil?

 

I don't know on his motor but a pretty common cause is cam chain guide debris that collects in the pan as the guide starts breaking up due to a gozillion heat and cool cycles and/or the occaisional overheating of the engine which would accelerate the problem. There are quite a number of the modular engines running around with 300,000 and 400,000 miles on them that have never been apart which can only be attributed to good maintainance. I haven't seen where the use of any particular oil has made a difference. I have 200,000 on my Mark VIII and have been using Mobil 1 since I bought it and my engine runs flawlessly as well as being spotless inside. I bought a used Mark VIII for my son that was owned by a diesel engineer who only used Ford's synthetic oil for the time he had it, just short of 100,000 miles and then my son had it for about 22,000 and only used synthetic oil until a careless driver totaled it. We kept the salvage and that engine was also spotless inside.
My personal belief is that if the engine is treated only to a good synthetic oil it could last for well over 500,000 miles of normal driving, provided it never sees a serious overheating or loss of oil.
Ford dyno tests these engines for more than a year before putting them into production and I am suprised that they don't publish a mileage cycle for cam or timing chain and guide replacement. I guess they just don't care as the engines will be well out of the warrantee period and it won't matter to them.
In any case I could go on and on about the value of good maintainence and the use of top quality lubricants but what it all comes down to is if you take care of your vehicle it will give you many more miles than if you don't.

 

Modular con rods use "cracked" caps. No two are alike since the process for making the cap literally has the cap "broken" away from the rod body. This assures an absolutely perfectly round bearing support with little or no machining necessary. You'll have to match the caps to the rods VERY carefully.
JL

 

I think you could have a machine shop check clearances and they could sort it out, or probably end up buying new rods. Considering you spun a rod, you should already have 2 new rods , the 1 you spun and the next to it rod that always gets taken out also.

 

Actually it 2-3 years engine test. My Dad test them.


What big issues is sludge build up on valve area it stick there. It best to stay 1 brand oil and change every 5K miles.

 

One weakness in the 5.4 is that it must use the oil that is specified on the oil-filler cap. Any variation can cause the spun-rod-bearing problem, even with an adequate level of oil in the oil pan. Spun rods typically happen on the 4 and 8 crank journal.

The rod sometimes has a three digit number printed on the side of the cap and on the side of the rod before it is fracured. The number is often difficult to see unless the light is at the correct angle. Rod "633" will match cap "633." This method of rematching the rods with the caps should work for some or even all of them. Some of the numbers may be faded or not even visible any more. Look carefully at the butt end of the rod cap. The flat area will have a slightly beveled edge on one side. The beveled edge must face the front of the engine. The bearings that spun may have discolored the rod caps due to heat. Match the darker ones up. However you match them, you must match the fractures on both sides of the rod caps with fractures on the rods. A good match should be obvious on both sides. A bad match should also be obvious. Keep matching them until you can barely see the fracture marks once they are snug. The caps and rods must match perfectly or the crank will bind when you try to turn it by hand. If the rods and caps are properly mated and torqued, you will be able to turn the crank with a little effort. It won't take more than a "normal" breaker-bar effort, though, with no cheater required. Be sure to replace your timing chains exactly as the book describes. A timing-chain error could shove a valve through the top of a piston on start up. Don't force anything and use common sense. Make sure these things are properly done before you reinstall the engine. The valve covers are difficult to remove once the engine is in place. Good luck.